<template>
 <div class="child">
    <h3>我是Child组件</h3>
    {{sum}}
 </div>
</template>

<script>
import {ref} from 'vue'
export default {
  name: "Child",
  /*
  setup() {
    let sum = ref(0)
    // return {sum}
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve({sum})
      }, 1000);
    })
  }*/
  async setup() {
    let sum = ref(0)
    // return {sum}
    let p = new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve({sum})
      }, 1000);
    })
    return await p
  }
}
</script>
<style>
.child {
  background-color: skyblue;
  padding: 10px;
}
</style>
